package com.esri.hadoop.hive;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.io.BytesWritable;
import org.apache.hadoop.io.IntWritable;

import com.esri.core.geometry.ogc.OGCGeometry;
import com.esri.core.geometry.ogc.OGCMultiPoint;
import com.esri.core.geometry.ogc.OGCMultiLineString;
import com.esri.core.geometry.ogc.OGCMultiPolygon;

@Description(
	name = "ST_GeometryN",
	value = "_FUNC_(ST_GeometryCollection, n) - return the nth ST_Geometry in the collection (1-based index)",
	extended = "Example:\n"
	+ "  SELECT _FUNC_(ST_GeomFromText('multipoint ((10 40), (40 30), (20 20), (30 10))'), 3) FROM src LIMIT 1;  -- ST_Point(20 20)\n"
	+ "  SELECT _FUNC_(ST_GeomFromText('multilinestring ((2 4, 10 10), (20 20, 7 8))'), 2) FROM src LIMIT 1;  -- ST_Linestring(20 20, 7 8)\n"
	)

public class ST_GeometryN extends ST_GeometryAccessor {
	static final Log LOG = LogFactory.getLog(ST_GeometryN.class.getName());

	public BytesWritable evaluate(BytesWritable geomref, IntWritable index) {
		if (geomref == null || geomref.getLength() == 0 || index == null) {
			LogUtils.Log_ArgumentsNull(LOG);
			return null;
		}

		OGCGeometry ogcGeometry = GeometryUtils.geometryFromEsriShape(geomref);
		if (ogcGeometry == null){
			LogUtils.Log_ArgumentsNull(LOG);
			return null;
		}

		int idx = index.get() - 1;  // 1-based UI, 0-based engine
		try {
			GeometryUtils.OGCType ogcType = GeometryUtils.getType(geomref);
			OGCGeometry ogcGeom = null;
			switch(ogcType) {
			case ST_POINT:
				LogUtils.Log_InvalidType(LOG, GeometryUtils.OGCType.ST_MULTIPOINT, ogcType);
				return null;
			case ST_LINESTRING:
				LogUtils.Log_InvalidType(LOG, GeometryUtils.OGCType.ST_MULTILINESTRING, ogcType);
				return null;
			case ST_POLYGON:
				LogUtils.Log_InvalidType(LOG, GeometryUtils.OGCType.ST_MULTIPOLYGON, ogcType);
				return null;
			case ST_MULTIPOINT:
				ogcGeom = ((OGCMultiPoint)ogcGeometry).geometryN(idx);
				break;
			case ST_MULTILINESTRING:
				ogcGeom = ((OGCMultiLineString)ogcGeometry).geometryN(idx);
				break;
			case ST_MULTIPOLYGON:
				ogcGeom = ((OGCMultiPolygon)ogcGeometry).geometryN(idx);
				break;
			}
			return GeometryUtils.geometryToEsriShapeBytesWritable(ogcGeom);
		} catch (Exception e) {
			LogUtils.Log_InternalError(LOG, "ST_GeometryN: " + e);
			return null;
		}
	}
}
